Persons who become stranded in large bodies of water due to boat mishaps or the like are in the best of circumstances difficult to locate. This situation is aggravated by the onset of wave action or darkness which can severely hamper rescue efforts, especially if these are being carried out from the air and over large areas. Additionally, even if a person is equipped with a suitable life vest which ensures that he/she stays afloat even while unconscious, as the onset of hypothermia in even relatively warm bodies of water can be fairly rapid, failure to locate and extract survivors from the water quickly can have dire results.
In order to improve the visibility of a person stranded in water the prior art reveals signalling devices comprising a small yet bright light source and battery pack. These are often fastened to the life vest by means of a lanyard or the like, and float, or are mounted directly on the upper part of the life vest and typically generate a flashing signal, or strobe. Additionally, such prior art devices often include a submersible switch which activates the flashing light source when the switch is placed in water. Such water activated switches are advantageous in settings where the wearer of the life vest is unconscious or otherwise unable operate the light source on his or her own (for example, as in the case of small children or infants). One drawback of these prior art devices is that they only function when in contact with water. Another drawback of these prior art devices is that no means are provided to extinguish the light source (for example, during daytime when the light is more or less invisible) and as a result, the batteries of such prior art devices become quickly depleted.
In order to overcome these drawbacks, means, such as a toggle switch, are provided in the prior art allowing the wearer to deactivate the light source, for example during the day when the visibility of the light source is adversely affected by the ambient light, thereby allowing the wearer to preserve the signalling device's battery pack.
One drawback of these prior art devices is that the toggle switch is easy to engage, which in some cases may lead to the flashing light source being inadvertently disconnected from the battery pack. Still another drawback is that such prior art devices uses either incandescent bulbs which are inherently fragile, or zenon strobes which are not suitable for use as steady state light sources. One other drawback is that if the flashing light source is deactivated using the toggle switch and the wearer leaves the water for a period of time, the water activated switch does not reactivate the flashing light source. As a result, if the wearer subsequently re-enters the water, the flashing light source will not be illuminated.